seminar code
09-08-2014, 12:36 PM
RSA/SHIFT SECURED IFFT/FFT BASED OFDM WIRELESS SYSTEM
[attachment=66799]
Abstract
The research on wireless system is to improve the
reliability and performance of wireless radio links. The
effects of (multi-path) radio propagation, modulation, and
coding and signal processing techniques on the spectrum
efficiency and performance of wireless radio networks are
studied, in particular Orthogonal Frequency Division
Multiplexing (OFDM) and related transmission methods.
But the multimedia information is not secured in the
wireless environment compared to that of wired
environment. In this paper, we have carried out a new
method of cryptographic algorithm over a future generation
(4G and above) wireless system called the OFDM (FFT (Fast
Fourier Transform) / IFFT (Inverse FFT)) technique using
Walsh Hadamard spreading codes. We have done the
simulation in MATLAB programming and the BER (Bit
Error Rate) vs. SNR (Signal-to-Noise Ratio) performance is
studied for multimedia signals (such as text, audio and
image) in an AWGN wireless channel. We have also
developed an algorithm for generating the Walsh codes and
the RSA secret keys. We found the results of our simulation
are very much satisfactory for practical implementation in
wireless systems.
INTRODUCTION
The mobile or indoor radio channel is characterized by
“multi-path reception”. The signal offered to the receiver
contains not only a direct line-of-sight radio wave, but
also a large number of reflected radio waves. These
reflected waves interfere with the direct wave, which
causes significant degradation of the performance of the
network. A wireless network has to be designed such a
way the adverse effect of these reflections is minimized.
Another critical design objective is high spectrum
efficiency. The latter should ensure that the network can
accommodate as many users as possible within a given
frequency band.
The effects of (multi-path) radio propagation,
modulation, and coding and signal processing techniques
on the spectrum efficiency and performance of wireless
radio networks are to be studied, in particular Orthogonal
Frequency Division Multiplexing (OFDM) and related
transmission methods[1,3]. OFDM is significantly less
sensitive to inter-symbol interference, because a special
set of signals is used to build the composite transmitted
signal. The basic idea is that each bit occupies a frequency
- time window ensures little or no distortion of the
waveform. In practice it means that bits are transmitted in
parallel over a number of frequency non-selective
channels. This technique is for instance used in Digital
Audio Broadcasting (DAB) [4].
But the multimedia information is not secured in the
wireless environment compared to that of wired
environment. So, there is a need to encrypt
OFDM TRANSMITTER AND RECEIVER
Consider a system with ‘N’ sub-carriers. The
incoming signal has a bit rate of R bits/second (bps)
with period T and base-band bandwidth B. When this
signal is passed through a Serial to Parallel (S/P)
converter, the incoming rate is reduced by a factor of
N by increasing the signal period by N times the
original period. However, in the frequency domain, the
bandwidth of the R/N bit streams is N times smaller
than the initial and width of the signal. Each bit stream
obtained from the S/P converter is then modulated to a
carrier. The modulated signals are then summed
together before transmission on the channel. Thus, if
OFDM is used in multi-carrier modulation, then N
modulators can be replaced by an Inverse Fast Fourier
Transform (IFFT) operation as shown in Figure
ENCRYPTION/DECRYPTION SYSTEM
The basic idea of our proposed cryptosystem is using
the combination of both RSA and Shift cipher algorithms.
The shift ciphering is a symmetric key cryptography
algorithm using a shared key for both encryption
(converting plain text to cipher text) and decryption
(converting cipher text to plain text) and here the ASCII
characters are substituted as numbers from 0 to 127 and
they are shifted according to a key and the shifted
numbers are transmitted and at the receiver the original
numbers are obtained again by shifting using a key which
is shared along with the transmitter key.
Voice encryption/decryption with IFFT/FFT OFDM
The below voice waveforms in Figure 4 (Input (top
waveform) (Transmitter), Output (bottom waveform)
(Receiver) and the Cipher (middle waveform) (Wireless
Medium)) represent the results of RSA/SHIFT Secured
IFFT/FFT Based OFDM Wireless System with the
OFDM model and with the RSA/SHIFT Secured method.
The Output waveform was observed at SNR of 10 dB
with little noise (audibility is same as the Input) but for
SNR of 12 dB we get the Output waveform audible
without error. The BER vs. SNR curve is plotted in
Figure 5
CONCLUSION
In this paper, the MATLAB simulation and the results of
RSA/SHIFT CIPHERED IFFT/FFT Based OFDM
multimedia wireless network in an AWGN were
presented.
RSA/SHIFT Cryptography implementation is
really a good one and it is very difficult for the
intruder or interceptor to get the multimedia
information.
IFFT/FFT based OFDM digital communication
system was studied and the results were good for
practical implementation and this also gives
additional security to the information over
wireless medium.
The various applications like text, image and
voice information were transmitted through
above systems and studied the Quality of
Service (QoS) requirements. The results are
extremely a convincing and coincident with
practical existing multimedia wireless
applications
[attachment=66799]
Abstract
The research on wireless system is to improve the
reliability and performance of wireless radio links. The
effects of (multi-path) radio propagation, modulation, and
coding and signal processing techniques on the spectrum
efficiency and performance of wireless radio networks are
studied, in particular Orthogonal Frequency Division
Multiplexing (OFDM) and related transmission methods.
But the multimedia information is not secured in the
wireless environment compared to that of wired
environment. In this paper, we have carried out a new
method of cryptographic algorithm over a future generation
(4G and above) wireless system called the OFDM (FFT (Fast
Fourier Transform) / IFFT (Inverse FFT)) technique using
Walsh Hadamard spreading codes. We have done the
simulation in MATLAB programming and the BER (Bit
Error Rate) vs. SNR (Signal-to-Noise Ratio) performance is
studied for multimedia signals (such as text, audio and
image) in an AWGN wireless channel. We have also
developed an algorithm for generating the Walsh codes and
the RSA secret keys. We found the results of our simulation
are very much satisfactory for practical implementation in
wireless systems.
INTRODUCTION
The mobile or indoor radio channel is characterized by
“multi-path reception”. The signal offered to the receiver
contains not only a direct line-of-sight radio wave, but
also a large number of reflected radio waves. These
reflected waves interfere with the direct wave, which
causes significant degradation of the performance of the
network. A wireless network has to be designed such a
way the adverse effect of these reflections is minimized.
Another critical design objective is high spectrum
efficiency. The latter should ensure that the network can
accommodate as many users as possible within a given
frequency band.
The effects of (multi-path) radio propagation,
modulation, and coding and signal processing techniques
on the spectrum efficiency and performance of wireless
radio networks are to be studied, in particular Orthogonal
Frequency Division Multiplexing (OFDM) and related
transmission methods[1,3]. OFDM is significantly less
sensitive to inter-symbol interference, because a special
set of signals is used to build the composite transmitted
signal. The basic idea is that each bit occupies a frequency
- time window ensures little or no distortion of the
waveform. In practice it means that bits are transmitted in
parallel over a number of frequency non-selective
channels. This technique is for instance used in Digital
Audio Broadcasting (DAB) [4].
But the multimedia information is not secured in the
wireless environment compared to that of wired
environment. So, there is a need to encrypt
OFDM TRANSMITTER AND RECEIVER
Consider a system with ‘N’ sub-carriers. The
incoming signal has a bit rate of R bits/second (bps)
with period T and base-band bandwidth B. When this
signal is passed through a Serial to Parallel (S/P)
converter, the incoming rate is reduced by a factor of
N by increasing the signal period by N times the
original period. However, in the frequency domain, the
bandwidth of the R/N bit streams is N times smaller
than the initial and width of the signal. Each bit stream
obtained from the S/P converter is then modulated to a
carrier. The modulated signals are then summed
together before transmission on the channel. Thus, if
OFDM is used in multi-carrier modulation, then N
modulators can be replaced by an Inverse Fast Fourier
Transform (IFFT) operation as shown in Figure
ENCRYPTION/DECRYPTION SYSTEM
The basic idea of our proposed cryptosystem is using
the combination of both RSA and Shift cipher algorithms.
The shift ciphering is a symmetric key cryptography
algorithm using a shared key for both encryption
(converting plain text to cipher text) and decryption
(converting cipher text to plain text) and here the ASCII
characters are substituted as numbers from 0 to 127 and
they are shifted according to a key and the shifted
numbers are transmitted and at the receiver the original
numbers are obtained again by shifting using a key which
is shared along with the transmitter key.
Voice encryption/decryption with IFFT/FFT OFDM
The below voice waveforms in Figure 4 (Input (top
waveform) (Transmitter), Output (bottom waveform)
(Receiver) and the Cipher (middle waveform) (Wireless
Medium)) represent the results of RSA/SHIFT Secured
IFFT/FFT Based OFDM Wireless System with the
OFDM model and with the RSA/SHIFT Secured method.
The Output waveform was observed at SNR of 10 dB
with little noise (audibility is same as the Input) but for
SNR of 12 dB we get the Output waveform audible
without error. The BER vs. SNR curve is plotted in
Figure 5
CONCLUSION
In this paper, the MATLAB simulation and the results of
RSA/SHIFT CIPHERED IFFT/FFT Based OFDM
multimedia wireless network in an AWGN were
presented.
RSA/SHIFT Cryptography implementation is
really a good one and it is very difficult for the
intruder or interceptor to get the multimedia
information.
IFFT/FFT based OFDM digital communication
system was studied and the results were good for
practical implementation and this also gives
additional security to the information over
wireless medium.
The various applications like text, image and
voice information were transmitted through
above systems and studied the Quality of
Service (QoS) requirements. The results are
extremely a convincing and coincident with
practical existing multimedia wireless
applications